Thinking Mathematically (6th Edition)

Published by Pearson
ISBN 10: 0321867327
ISBN 13: 978-0-32186-732-2

Chapter 5 - Number Theory and the Real Number System - 5.1 Number Theory: Prime and Composite Numbers - Exercise Set 5.1 - Page 256: 83


13 is not a Germain prime.

Work Step by Step

A prime number $p$ is a Germain prime if $2p+1$ is also a prime. This means that 13 is a Germain prime if: $2(13)+1$ is also a prime number. Note that $2(13)+1=27$, which is not a prime number. Thus, 13 is not a Germain prime.
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